A car at 54 km/h brakes with a constant deceleration of 3 m/s squared. How far does it travel while braking to a stop?
Answer and explanation
Correct answer: D. 37.5 m
- Step 1: Speed = 54 / 3.6 = 15 m/s. Use d = v squared / (2a). Step 2. d = 15 squared / (2 x 3) = 37.5 m. Answer: 37.5 m. Why not the others: 75 m: 75 m forgets the factor 2 in v squared over 2a. 5 m: 5 m is the braking time in seconds, not a distance. 90 m: 90 m mixes in one second of extra travel.
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